The present invention relates to data cartridge library systems that are capable of storing a plurality of data cartridges, such as tape cartridges, in a storage array and selectively moving a data cartridge between the array and a drive that transfers data between a host computer and a recording medium located within a data cartridge device.
Data cartridge library systems are primarily used to archive data, i.e. store data that is or may be important to the user of a computer system but not immediately needed by the user. To elaborate, the typical library system receives data from a host computer and stores the data in one or more data cartridges. When the host computer requires some of the data that was previously stored in a data cartridge, a request for the data is sent from the host computer to the library system. In response, the library system locates the data cartridge that contains the data being requested and transmits the data to the host computer.
The typical data cartridge library system is comprised of a cartridge holder with a plurality of storage slots that are used for storing a plurality of data cartridges, a player/recorder device for reading data that has been stored on the recording medium located within a data cartridge and/or writing data onto the recording medium, and a transport device for moving data cartridges between the cartridge holder and the player/recorder device. To store data in a data cartridge, the library system initially uses the transport device to load a data cartridge into the player/recorder device. Once the data cartridge has been loaded into the player/recorder device, the drive records or writes data from the host computer onto the recording medium located within the data cartridge. After all of the data has been recorded, the transport device removes the data cartridge from the player/recorder device and places the data cartridge in one of the slots of the cartridge holder. Generally, at some later time, the host computer has a need for the data stored on the data cartridge and issues a request for the data to the library system. In response, the library system identifies the slot of the cartridge holder in which the data cartridge on which the needed data is stored, causes the transport device to move the data cartridge from the slot to the player/recorder device. Once the data cartridge is loaded into the player/recorder, the desired data on the recording medium located within the cartridge is read by the player/recorder and passed on to the host computer.
The present invention addresses the need for a low-cost data cartridge library system by reducing the number of certain components, especially expensive components, that are needed to perform certain functions within the library. Cost reduction is also achieved with respect to particular library functions by using less expensive, low-precision componentry in combination with componentry that compensates for the low-precision and still provides a reduced cost relative to high-precision componentry.
One embodiment of the invention provides a data cartridge library with a picker assembly that utilizes a single electro-mechanical device to accomplish the following functions: (1) grasping a data cartridge located in either a slot of the data cartridge holder or in the drive; (2) retracting a grasped cartridge a sufficient distance from the holder or the drive so that the cartridge can be moved to another location within the library; (3) inserting a grasped cartridge into a slot of the data cartridge holder or into the drive; and (4) releasing a data cartridge that has been inserted into either a slot of the data cartridge holder or the drive. In contrast, most known data cartridge library systems use two electro-mechanical devices to accomplish the noted functions, one to perform the grasping and releasing function and the other to accomplish the retracting and inserting functions. In one embodiment, a single electro-mechanical device is used to move a cam that contacts a cam follower surface on a grasping portion of the picker, i.e. the portion of the picker that is capable of grasping, retracting, inserting and releasing a data cartridge, in a fashion that accomplishes each of the noted functions. In one embodiment, the cam follower surface includes two distinct cam follower surfaces that are contacted by different portions of the cam. Interaction between the cam with the first cam follower surface causes the grasper to be displaced either towards or away from the data cartridge holder or drive to accomplish the retraction and insertion functions, respectively. The grasping and releasing of a data cartridge is attributable to the interaction between the cam and the second cam follower surface.
A further embodiment of the invention provides a data cartridge library with a picker assembly that limits the force applied to the picker assembly during operations involving the drive. For instance, during a retraction operation, variations in the operation of one drive from another drive may result in a data cartridge being positioned closer to the picker by one drive than another drive. A data cartridge that is positioned closer to the picker than anticipated will result in the picker contacting the data cartridge sooner than expected and a force being applied by the data cartridge to the picker that could damage the picker and/or the data cartridge. Similarly, during an insertion operation, the drive may be positioned closer to the picker than anticipated and produce a similar problem. The problems can be addressed by either time consuming and perhaps expensive adjustment of the components and/or by employing high precision design techniques. The present invention reduces the need for such approaches by providing a picker with a force limiter or compensator. In one embodiment, the picker assembly employs a spring between the grasping portion of the picker assembly, i.e. the portion of the picker assembly that is used to grasp, retract, insert and release a data cartridge, and a portion of the picker that contributes to moving the grasper towards and away from the drive to compensate for the noted variations in distance of a cartridge during a retraction operation and factors that may result in an undesirable force being applied to the picker during an insertion operation. The spring permits the grasping portion of the picker assembly to move relative to the portion of the picker assembly that is used to move the grasper when a data cartridge is contacted earlier than anticipated.
Another embodiment of the invention provides a data cartridge library with a picker assembly that includes a grasper, i.e. the portion of the picker assembly that is used to grasp, retract, insert and release a data cartridge, and a device for moving the grasper during insertion and retraction operations such that the velocity of the grasper varies in a substantially sinusoidal manner. The permits the grasper to be moved at a slower velocity when near the data cartridge holder/drive and a faster velocity further from the cartridge holder/drive. In one embodiment, a circular gear with an attached cam that contacts a cam follower surface associated with the grasper is used in the retraction and insertion operations. The gear provides the sinusoidal aspect of the motion. By moving the grasper in a sinusoidal manner, greater force can be applied to a data cartridge during the point in the insertion and retraction operations involving the drive. To elaborate, some drives require that a data cartridge be forcefully inserted into and/or retracted from the drive. The greater force with the slower speed provide reliable insertion/retraction of a data cartridge into/from such drives. In another embodiment, the sinusoidal movement of the grasper is combined with the force limiter. This permits the appropriate amount of force to be applied to a data cartridge during insertion/retraction of a data cartridge with respect to the drive, while also limiting the applied force to prevent damage to the picker assembly and/or the data cartridge.
Another embodiment of the invention provides a data cartridge library with picker assembly that can be controlled during insertion and extraction movement to reduce wear on the componentry and thereby reduce maintenance and/or replacement associated costs. Known picker assemblies operate such that the grasper is always returned to the fully retracted position following the insertion of a data cartridge into either the data cartridge holder or the drive. The fully retracted position is the point at which a transport device that is used to move the picker assembly to various locations within the library can move the picker assembly when the picker assembly is grasping a data cartridge. Insertion of a data cartridge that is being held by the grasper commences by moving the grasper towards either the data cartridge holder or drive and continuing with this movement until the data cartridge can be released. Following insertion of the data cartridge, known data cartridge library systems return the picker assembly to the fully retracted position. Subsequently, to retract a data cartridge from either the data cartridge holder or the drive, the known library systems must move the picker assembly from the fully retracted position to a point at which a data cartridge can be grasped.
The present invention avoids the need to move the grasper from the fully retracted position when the grasper is not holding a data cartridge to grasp a data cartridge located in either the data cartridge holder or drive. The present invention provides a picker assembly that can be positioned at a point that is closer to one of the data cartridge holder and drive than the fully retracted position when the grasper is not holding a data cartridge. In one embodiment, the picker assembly provides the ability to position the grasper at substantially the extended position at which the grasper grasps or begins to grasp a data cartridge located within the data cartridge holder or drive. Consequently, a subsequent retraction of a data cartridge from either the data cartridge holder or drive merely requires the picker assembly to grasp the cartridge and then retract the cartridge for subsequent positioning elsewhere in the library, thereby avoiding the need to move the picker from the fully retracted position as a preclude to grasping the data cartridge. In another embodiment, the picker assembly employs a grasper with two members for use in grasping opposite sides of a data cartridge that move linearly towards and away from one another in grasping and releasing a data cartridge, respectively. By moving the members in a linear manner, the picker assembly can positioned closer to the cartridge holder/drive than picker assemblies that grasp a data cartridge using members that rotate about a pivot point. In another embodiment, the two members are each L-shaped to further facilitate the positioning of the picker assembly close to the cartridge holder or drive.
Yet another embodiment of the invention provides a data cartridge library system that employs a transport mechanism for moving a picker assembly that makes use a guide mechanism which defines at least part of the space in which the picker assembly is constrained to move to also form part of the mechanism that is used to move the picker assembly within the defined space. In one embodiment, the transport assembly includes two opposing surfaces and a drive device for use in moving the picker assembly. A portion of the drive device is operatively attached to the picker assembly and is used to apply force to the opposing surfaces to move the picker assembly to a desired location within the library. Consequently, the opposing surfaces and the portion of the drive device that is attached to the picker act both to: (1) constrain the space within which the picker assembly can move; and (2) cooperate in moving the picker assembly from one location to another within the library. In this embodiment, the opposing surfaces and portion of the drive device associated with the picker assembly constrain movement of the picker assembly in two orthogonal dimensions but not the third orthogonal dimension. As a consequence, it is possible to displace the picker such that the drive device is no longer contact the opposing surfaces. To address this problem, another embodiment uses a second pair of opposing surfaces to constrain the movement of the picker assembly in the third dimension.
In one embodiment, the first opposing surface is comprised of a first pair of racks that are substantially parallel to one another and face one direction. The second opposing surface is comprised of a second pair of racks that are substantially parallel to the first pair of racks but face in the opposite direction. Operatively attached to the picker assembly is a gear system that engages the racks and is used in moving the picker assembly within the space defined by the racks. The gear system operates such that the gears that engage the first pair of racks rotate oppositely from the gears that engage the second pair of racks in moving the picker assembly up and down the racks. The gear system and racks cooperate to constrain the space within which the picker assembly can move in two dimensions. A pair of surface that are substantially perpendicular to the directions that the rack face are used to constrain the movement of the picker assembly in the third dimension.
Another embodiment of the invention provides a data cartridge library with a face plate extension to the face plate of the drive that facilitates insertion of a data cartridge into a drive, thereby reducing the need for high precision in the componentry and/or design of the library, especially with respect to the picker assembly, transport device for moving the picker assembly, and the positional relationship of the picker assembly, transport device and drive. Generally, a face plate extension positions a data cartridge that is misaligned for insertion into a drive by using ramps to apply aligning forces to the surfaces of the data cartridge as the cartridge is being moved towards the drive. A data cartridge is generally a box-like structure with a top surface, a bottom surface, first side surface, second side surface, front surface and back surface. The front surface is the surface of the data cartridge that initially enters the drive. Known face plate extensions provide ramps for contacting at least one and potentially all of the top, bottom, first side and second side surfaces of a misaligned data cartridge to align the data cartridge for insertion into the drive. One such face plate extension is essentially a rectangularly shaped funnel in which a first pair of oppositely disposed ramps are positioned to contact the sides of the cartridge, and a second pair of oppositely disposed ramps are positioned to contact the top and bottom of the cartridge.
The present invention provides a face plate extension that has recognized that certain types of data cartridges have a discontinuity that permits an aligning structure to be realized in which a misaligned data cartridge can be aligned for insertion into the drive by applying an aligning force to one and at most three of the top, bottom, first side and second side surfaces. In one embodiment, the face plate extension provides a ramp structure that applies the necessary aligning forces to one and at most two of the surfaces of a misaligned cartridge. The face plate extension can be used, for example, with a TRAVAN tape cartridge. A TRAVAN tape cartridge has a bottom surface and a top surface with a step discontinuity. The face plate extension provides a first ramp structure for contacting either or both of the top and bottom surface to correct one possible type of misalignment of the data cartridge. A second ramp structure makes use of the discontinuity on the top surface of the cartridge to correct a second type of misalignment. In the case of a TRAVAN tape cartridge, the step in the top surface of the cartridge is utilized to correct a second type of misalignment. In one embodiment, the first ramp structure is located closer to the picker than the second ramp structure. Consequently, the face plate extension operates to sequentially align a misaligned data cartridge, i.e. a first type of misalignment is corrected followed by the correction of a second type of misalignment.
The present invention also provides a removable data cartridge holder for use in a data cartridge library that includes an open-sided box-like structure for holding a plurality of data cartridges, a dust cover and an coupling apparatus for attaching the dust cover to the data cartridge library when box-like structure is in use, i.e. mounted in the library with the opening of the box-like cover exposed so that data cartridges can be moved in and out of the box-like structure. When the box-like structure is dismounted from the library, the dust cover can be placed over the opening to protect any data cartridges contained in the box-like structure. In one embodiment, the coupling apparatus operates to attach the dust cover to the box-like structure. In another embodiment, the dust cover possesses a U-shaped cross- section and the coupling apparatus serves to connect the dust cover to the box-like structure such that the box-like structure is nested inside the U-shaped dust cover. A further embodiment of the holder that provides a U-shaped dust cover and the noted nesting feature includes a connecting device for adhering the box-like structure and attached dust cover to a surface within the library. In one embodiment, the connecting device also provides a reference surface that facilitates the desired orientation of the box-like structure within the library housing.
The present invention further provides a data cartridge holder that includes a cantilevered retaining member for holding a data cartridge in the holder, thereby inhibiting the accidental displacement or removal of the data cartridge from the holder. The data cartridge holder is a box-like structure with an open side that permits data cartridges to be inserted/removed into/from the holder. The cantilevered retaining member has a fixed end, which is attached to the box-like structure, and a free or floating end that is located further from the opening than the fixed and, in response to the insertion or extraction of a data cartridge, is displaced. To elaborate, during insertion of a data cartridge, the free end of the member is initially displaced to permit the cartridge to be fully inserted into the holder. However, upon complete insertion the free end of member returns to its unflexed or initial position to engage a notch or similar structure associated with the data cartridge and thereby inhibit accidental removal of the cartridge from the holder. In one embodiment, the cantilevered retaining member has a dog-leg shape with a first portion that is located between the point at which the member is attached to the housing and an intermediate point on the member. The portion of the member is disposed at an acute angle to the side wall of the holder and operates as a ramp to aid in positioning a data cartridge during insertion into the holder. The second portion of the member operatively engages the notch or other feature on the cartridge to hold the cartridge in place. In one embodiment, the second portion of the member is substantially parallel to the side wall of the holder. In yet a further embodiment, a second cantilevered retain member is disposed in the holder to engage another notch or other feature associated with a data cartridge.
The present invention also provides a data cartridge holder that includes an orientation device that inhibits the insertion of improperly oriented data cartridges of the type that include a door which can be rotated about a pivot point to expose the recording media within the cartridge. When a data cartridge of this type is improperly oriented for insertion into the holder, the orient device operates to open door of the cartridge. The opened door subsequently engages a portion of the cartridge holder such that further insertion of the data cartridge is inhibited. It is desirable to insert a data cartridge into the holder in the same orientation as the cartridges are inserted into the drive, i.e. front face first, to simplify the design and operation of the picker assembly. In contrast, if a cartridge is inserted into the data cartridge holder with a different orientation than when the cartridge is inserted into the drive, the picker assembly must provide the ability to reorient the data cartridge between the time the cartridge is removed from the holder and the time the data cartridge is inserted into the drive.